I think Kroc was implying that you can't run native applications in Firefox OS, so no other browsers implicitly as well. But it's a design restriction, not some sick legal prohibition so it's not comparable. It's like saying that JVM discriminates the native code.

Apple's reason is completely technical. JIT engines are not allowed at all.

That's not a technical reason. For it to be a technical reason, there would have to be a full explanation as to why they do not allow JIT runtimes. Until then, it's a political restriction. They don't want someone like Google showing them up with V8 as opposed to Apple's own js runtime. It really is that simple.